Pinyin is a phonetic system for transcribing Mandarin Chinese using the Roman alphabet. In a pinyin transliteration, the phonetic pronunciations of Chinese characters can be mapped to syllables composed of Roman letters. Pinyin is commonly used to input Chinese characters into a computer via a conversion system. For a given pinyin input, the conversion system can output Chinese characters that most likely correspond to the pinyin input. Such a system often incorporates statistical language models to improve conversion accuracy. However, while conventional language models can be helpful for determining commonly used Chinese character sequences, they can be less successful at determining Chinese character sequences that are not frequently used in the Chinese language. This can present difficulties to users who frequently need to input particular sequences of Chinese characters that are less common in the Chinese language, such as the names of friends or family members or the names of locations frequented by the user.